The present invention relates to magnetic devices. More particularly, the present invention relates to a magnetic device that employs a high frequency oscillating field.
Two general techniques for magnetically recording information on a storage medium include longitudinal recording and perpendicular recording. In longitudinal recording, the direction of the magnetization in a plane of the storage medium is altered in a manner to store information. In perpendicular recording, the magnetization of the storage medium is altered in a direction that is perpendicular to the plane of the medium. With the magnetization direction perpendicular to the plane of the medium as opposed to parallel with the plane, information can be stored at higher density.
There has been an ongoing effort to increase the bit densities in magnetic recording. Bit density refers to the number of bits that can be written to the storage medium in a given length, area, or volume. The size of such a flux transition is related to the size and focus of a magnetic write field generated by a magnetic head. One traditional type of magnetic head is known as an inductive head, which uses a current passed through a coil of wire. This causes a magnetic field to be generated at the pole tip or tips of the head that is used to write data to the magnetic medium.
There is also an ongoing effort to use magnetic storage media that have a high coercivity. This type of media requires stronger and a more focused write field to impress a flux reversal. One approach to providing a stronger write field is to incorporate a device adjacent to the tip of the write pole that produces a magnetic field to reduce the coercivity of the magnetic medium near the write pole. This allows data to be written to the high coercivity medium with a lower magnetic field from the write pole. However, many current designs of such write assist devices consume high levels of power to generate the assist field, and the frequency of the assist field produced by these write assist devices is not easily controlled.